JPH10256710A - Method and apparatus for cleaning through-hole of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for cleaning through-holes of a printed wiring board which can surely perform the cleanings of the wettabilities in the through-holes and the inner wall surfaces of the through- holes, without damaging the surface of the printed wiring board. SOLUTION: A cleaning apparatus is constituted of a printed wiring board 2, having a plurality of through-holes 1 with small diameters, a cleaning vessel 3 whose water floats the printed wiring board 2 in the state of it being dipped thereinto and which holds a predetermined water level H, a mesh-form protection member 4 for covering therewith at least the top surface side 2a of the printed wiring board 2, and a water-sucking means 5 which moves a cleaning water Q of the cleaning vessel 3 horizontally along the printed wiring board 2 and the mesh-form protection member 4 floated on a water surface W of the cleaning vessel 3 and so cleans the plurality of through-holes 1, formed in the printed wiring board 2 that the holes 1 such the cleaning water Q of the cleaning vessel 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cleaning a through hole in a printed wiring board, and more particularly to a method and an apparatus for cleaning the through hole efficiently without damaging the surface of the printed wiring board and wetting the inner wall surface of the through hole. TECHNICAL FIELD The present invention relates to a method and an apparatus for cleaning a through hole of a printed wiring board, which can provide a property.

[0002]

2. Description of the Related Art In general, a printed wiring board made of a resin material or the like has a wiring circuit formed on the front and back surfaces of a plurality of substrates laminated together and a plurality of through-holes for mounting components and conducting circuits. Are formed. The through hole is generally formed by a drill or the like,
For this reason, after forming the through hole, chips and dust are often attached to the inner wall surface of the through hole. If such chips and dust are not removed in advance, copper and solder plating etc. will be performed later. The sticking becomes worse and may become a defective product. The same applies to the case where the residual air bubbles in the through hole are not removed.

[0003] Therefore, as a through hole cleaning step in a conventional printed wiring board manufacturing process, for example, water is sprayed on a through hole formed in the printed wiring board, or a cleaning method, or a printed wiring board is immersed in a cleaning solution. Washing the through-hole by rocking it, applying a shock to the printed wiring board in the cleaning solution, dropping the printed wiring board horizontally to the surface of the cleaning solution for cleaning, and further rolling the printed wiring board with a roll Various methods such as a method in which water is supplied from above and water is sucked from below to wash through holes (Japanese Patent Publication No. 4-39238), and the method is carried out in such a manner that the through hole is horizontally moved while being clamped. I have.

[0004]

However, in the conventional method, the thickness of the printed wiring board is large (for example, 1.6 mm).
If the through hole has a very small diameter (for example, about 0.3 mm) or a material with a high aspect ratio, it is difficult to completely clean multiple through holes. there were. For example, in the above method: In case of cleaning method by spraying water on through hole of printed wiring board.

If the processing time for one through hole is short and the processing time is extended, the loss of the cleaning liquid increases. There is a possibility that a part that does not hit the shower at all may be formed, it is difficult to complete the treatment stochastically, and the establishment for passing small water droplets with respect to the through hole diameter (about 0.3 mm) is poor. There is a possibility of uneven processing depending on the spray angle.

[0006] The efficiency of cleaning through holes is several percent of the efficiency of the shower, which is inefficient. That is, the surface area of the through hole is several percent of the surface area of the substrate, and the remainder is 90% or more. . A method of cleaning through holes by immersing a printed wiring board in a cleaning solution and rocking the printed wiring board.

[0007] The passage speed of the liquid in the through hole is slower than the rocking speed at the maximum, and is slow, and since it is in the solution, the passage of the through hole is poor due to the resistance of water pressure. . A method of impacting a printed wiring board in a cleaning solution.
Only treatment to remove air bubbles in through hole, 100%
Cannot be treated, and because the solution is in a solution, the passage through the through hole is poor due to water pressure resistance. . A method in which a printed wiring board is dropped horizontally on the surface of the cleaning solution to be cleaned. It is difficult to make the parallelism with the water surface and the drop speed uniform, and the work varies widely, and uniform treatment is difficult. . A method in which a printed wiring board is horizontally moved by being sandwiched by rolls, and water is supplied from above and suctioned from below to wash through holes during the moving process. There is a problem that the configuration is complicated, the entire apparatus becomes large, and the cost increases.

The present invention has been devised in view of such a conventional problem, and does not damage the surface of the printed wiring board, and ensures the wettability in the through hole and the cleaning of the inner wall surface of the through hole. It is an object of the present invention to provide a method and an apparatus for cleaning through holes in a printed wiring board, which can be performed.

[0009]

In order to achieve the above object, the present invention provides a cleaning container in which a printed wiring board having a plurality of through holes is floated in a immersed state and holds a predetermined water level. A stitch-shaped protective member that covers at least the upper surface side of the printed wiring board, and a printed wiring board that is moved horizontally along the printed wiring board and the stitch-shaped protective member that floats on the water surface in the cleaning container; And a water suction means for performing cleaning by sucking the cleaning liquid in the cleaning container from the plurality of through holes formed in the cleaning container.

A cleaning liquid supply / discharge means for maintaining a constant water level in the cleaning container, a circulation device for circulating the cleaning liquid,
Means for holding the printed wiring board horizontally on the water surface in the washing container via a stitch-shaped protective member. The present invention is configured as described above, and a printed wiring board having at least an upper surface side covered with a stitch-shaped protective member is floated horizontally on a water surface in a cleaning container adapted to hold a predetermined water level, and In a state where the printed wiring board is set in the container via the protection member, the water suction means is moved over the entire substrate along the upper surface of the printed wiring board through the stitched protection member, and the plurality of printed wiring boards are formed on the printed wiring board. The cleaning liquid in the cleaning container is suctioned from the through hole to wash the through hole, thereby protecting the surface of the printed wiring board, thereby providing wettability to the inner wall surface of each through hole and simultaneously adhering to the inner wall surface of the through hole. It is possible to perform cleaning by reliably sucking and removing cutting chips, dust and the like.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a cleaning apparatus for carrying out a method for cleaning a through hole of a printed wiring board according to the present invention. The cleaning apparatus includes a printed wiring board 2 having a plurality of small-diameter through holes 1 formed thereon, and A cleaning container 3 that floats the printed wiring board 2 in a immersed state and holds a predetermined water level H; a stitch-shaped protection member 4 that covers at least the upper surface 2a of the printed wiring board 2; The cleaning liquid in the cleaning container 3 is moved from the plurality of through holes 1 formed in the printed wiring board 2 in the horizontal direction along the printed wiring board 2 floated on the water surface W in the container 3 and the stitch-shaped protection member 4. And a water suction means 5 for performing cleaning by sucking Q.

The cleaning container 3 includes the printed wiring board 2.
Is formed in a box shape in cross section so as to maintain a predetermined water level H with an area capable of storing the washing container 3 in a horizontal state.
A cleaning liquid discharge port 6 for maintaining the cleaning liquid Q at a predetermined water level H is formed on one side surface, and a level detector 7 provided in the cleaning vessel 3 is provided on the other upper part of the cleaning vessel 3. A cleaning liquid supply nozzle 8 for sequentially supplying the cleaning liquid Q is provided.

The predetermined water level H of the cleaning liquid Q in the cleaning container 3 is at least about の of the thickness of the printed wiring board 2 when the cleaning liquid Q is sucked from the through hole 1 by the water suction means 5. It refers to the degree of soaking. When the cleaning liquid Q is suctioned from the plurality of through holes 1 formed in the printed wiring board 2 by the water suction means 5 on the opposed inner wall surfaces of the cleaning container 3, the protection member 4 and the printed wiring board 2 are attached. Holding means 9a and 9b for holding the cleaning liquid 3 in the cleaning liquid Q of the cleaning container 3 are provided.
Is configured to be able to turn about the hinge 10 as a fulcrum.

The mesh-shaped protective member 4 that covers at least the upper surface 2a of the printed wiring board 2 is a mesh formed by meshing resin fibers or metal fibers into a mesh inside a rectangular support frame 11. 12 are stretched.
In addition, it is also possible to use a punch metal or the like as the protection member 4. Further, in this embodiment, the protective member 4 is configured to cover only the upper surface 2a of the printed wiring board 2, but the printed wiring board 2 is formed by two protective members 4.
It is also possible to cover the upper and lower surfaces 2a, 2b.

Next, a water suction means 5 for sucking the cleaning liquid Q from the through hole 1 for cleaning includes a vacuum nozzle 14 having a rubber-like vacuum pad 13 attached to the tip thereof, and a suction pipe 15 having the vacuum nozzle 14 attached thereto. , A cleaning liquid suction pump 16 and the water suction means 5.
When the operator moves in a horizontal direction along the printed wiring board 2 and the stitch-shaped protection member 4, the operator manually or automatically moves the robot by a robot or the like.

The cleaning liquid Q sucked by the water suction means 5 is:
It is also possible to discharge it to the outside or return it to the inside of the cleaning container 3 again by the cleaning liquid circulation circuit 17 as shown in FIG. The cleaning liquid circulation circuit 17 includes a circulation pipe 18 connecting the cleaning liquid discharge port 6 and the cleaning liquid supply nozzle 8, a circulation pump 19, a filter 20 for filtering the cleaning liquid Q, and a cleaning vessel 3 for filtering the cleaning liquid Q based on the level detector 7. The circulation pipe 18 is connected to a discharge pipe 22 for discharging the cleaning liquid Q sucked by the water suction means 5.

With such a configuration, the cleaning liquid Q in the cleaning container 3 can always maintain a constant water level H.
Further, the cleaning operation of the through hole 1 can be automatically performed. Next, a through hole cleaning method for the printed wiring board 2 will be described. First, as shown in FIG. 1, the upper surface 2a of the printed wiring board 2 is horizontally covered with a stitch-shaped protective member 4 on a water surface W in a cleaning vessel 3 in which a predetermined water level H is held. And holding means 9
a, 9b.

From such a state, as shown in FIGS. 2 and 3, the water suction means 5 is moved back and forth along the upper surface of the printed wiring board 2 through a stitch-like protective member 4 manually or by using a robot. Alternatively, the cleaning liquid Q in the cleaning container 3 is suctioned from the plurality of through holes 1 formed in the printed wiring board 2 via the cleaning liquid suction pump 16 while being moved in the left-right direction, and the through holes 1 are sequentially washed.

The cleaning liquid Q sucked by the water suction means 5
Is discharged to the circulation pipe 18 of the cleaning liquid circulation circuit 17 connected to the discharge pipe 22, and the cleaning liquid Q filtered by the filter 20 by the circulation pump 19 is supplied to the cleaning liquid supply nozzle 8
The water is supplied to the cleaning vessel 3 so that the water level is kept at a constant level H. By cleaning the through holes 1 of the printed wiring board 2 by the above-described method, wettability is imparted to the inner wall surfaces of the respective through holes 1 and, at the same time, chips, dust and the like adhering to the inner wall surfaces of the through holes 1 are provided. Can be surely removed by suction to perform washing.

[0020]

The present invention has the following advantages because it is constructed as described above. . The wettability in the through hole and the cleaning of the inner wall surface of the through hole can be surely performed without damaging the surface of the printed wiring board. . The treatment time can be adjusted as compared with the spray method, and the through-hole portion through which the water suction means passes can be completely washed. . There is no effect on the washing angle, there is little variation in work, and only the inside of the through hole can be selectively treated. . Compared to the swinging method during cleaning, the suction force affects the passing speed of the cleaning liquid in the through hole, and a high speed and amount can be obtained, and the energy in this time can physically clean the through hole. And the effect of removing foreign matter and film is improved. . Because of the treatment between gas and liquid, the resistance is reduced, and the liquid permeability is improved. . Compared with the conventional impact method, there is almost no possibility that air bubbles remain because the cleaning liquid is forcibly passed. . Since the configuration is relatively simple, cleaning can be performed at low cost, and workability and productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a cleaning apparatus for performing a through-hole cleaning method for a printed wiring board according to the present invention.

FIG. 2 is a partial cross-sectional view showing a step of cleaning a printed wiring board by a water suction unit.

FIG. 3 is a partial cross-sectional view showing a step of cleaning a printed wiring board by water suction means.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Through hole 2 Printed wiring board 2a Upper surface side of printed wiring board 3 Cleaning container 4 Protective member 5 Water suction means 6 Cleaning liquid outlet 7 Level detector 8 Cleaning liquid supply nozzle 9a, 9b Holding means 10 Hinge 11 Support frame 12 Mesh 13 Vacuum pad 14 Vacuum nozzle 15 Suction pipe 16 Cleaning liquid suction pump 17 Cleaning liquid circulation circuit 18 Circulation pipe 19 Circulation pump 20 Filter 21 Open / close valve 22 Discharge pipe Q Cleaning liquid H Water level W Water level in cleaning vessel

Claims (4)

[Claims] 1. A printed wiring board having at least an upper surface covered with a stitch-like protective member is floated horizontally on a water surface in a cleaning container adapted to hold a predetermined water level, and the protective member is placed on the cleaning container. With the printed wiring board set in place, the water suction means is moved over the entire substrate along the upper surface of the printed wiring board via the stitched protective member, and the cleaning container is removed from the plurality of through holes formed in the printed wiring board. A through hole cleaning method for a printed wiring board, wherein the through hole is cleaned by sucking a cleaning liquid in the inside. 2. The through hole cleaning method for a printed wiring board according to claim 1, wherein the cleaning liquid in the cleaning container is circulated at a constant water level. 3. A washing container which floats a printed wiring board having a plurality of through holes formed therein while dipping the printed wiring board and maintains a predetermined water level, and a stitch-like protection for covering at least an upper surface side of the printed wiring board. The member and the printed wiring board floated on the water surface in the cleaning container and moved in a horizontal direction along the stitch-shaped protective member, and the cleaning liquid in the cleaning container is suctioned from a plurality of through holes formed in the printed wiring board. A through-hole cleaning apparatus for a printed wiring board, comprising: a water suction means for performing cleaning. 4. A cleaning liquid supply / discharge means for maintaining a constant water level in the cleaning container, a circulating device for circulating the cleaning liquid, and the printed wiring board on a water surface in the cleaning container via a stitch-shaped protective member. 2. A through hole cleaning apparatus for a printed wiring board according to claim 1, further comprising means for horizontally holding said through hole.